Chlorinated solvents are the most common class of ground water contaminants detected in hazardous waste sites in the U.S. The Agency for Toxic Substances and Disease Registry (ATSDR) has repeatedly listed chlorinated solvents and their degradation products as the most frequently detected group of priority contaminants. Due to the unique characteristics of each site, the remediation of these compounds is often met with a variety of obstacles inherent to both the target organics and the environmental conditions.
The use of naturally occurring microbes to facilitate the degradation of target organics is well known in the art. Biotic degradation pathways use a series of slow sequential reactions to convert chlorinated solvents into harmless byproducts via electron exchange. Natural attenuation of these contaminants is enhanced in the presence of an electron donor, food source, electron acceptor, and/or substrate for the microbes. Previously, this enhancement has been sought using a variety of natural and chemical additions to contaminated soil and/or ground water, such as kelp and zero-valent iron. However, some environmental conditions limit the effectiveness of these materials, and thus limit the extent of decontamination that may occur. Additionally, biotic dechlorination is often associated with the formation of harmful daughter products (for example, cis- and trans-dichloroethene and vinyl chloride), and material that both reduces the formation of these byproducts and overcomes environmental limitations is needed.
Traditionally, sulfate-bearing ground waters were thought not amiable for reductive dechlorination. The reduction of sulfate to sulfide, a compound toxic to microbes, inhibits biological activity and thus prevents natural attenuation. In order to sustain natural attenuation, sulfide concentration must be reduced. The current state of the art involves attempting to minimize sulfide concentration ex situ or by the introduction of sulfate reducing microbes. As such, there is a need for a material which will diminish the presence of sulfide in situ without the addition of new microbes.